XVI International Botanical Congess

Glycerol-3-phosphate dehydrogenase (GPD) is a well known key enzyme for osmotic stress tolerance in microorganisms, which functions by accumulating glycerol as a compatible solute. We have cloned the GPD gene from P. sajor-caju in order to study whether microbial origin GPD also functions in higher plants for osmotic stress resistance. A complete GPD cDNA was isolated by RT-PCR using the primers derived from a conserved region within the GPD genes of Basidiomycetes. This cDNA contains an uninterrupted open reading frame of 1,005 nucleotides which encodes a polypeptide of 335 amino acids. Sequence analysis showed 76% and 78% sequence homology at amino acid level with the GPD genes of B. edulis and L. deterrimus, respectively. A quantitative RT-PCR analysis showed that the expression of GPD gene is highly induced by various osmotic stress including salt, cold, or dry treatment with different expression kinetics by each treatment. By gain-of-function experiments, we confirmed that overexpressed heterologous GPD gene can provide a great osmotic stress resistance in transgenic yeast cells. The complete P. sajor-caju GPD cDNA was fused to CaMV35S promoter and then introduced into potato plants. Several transgenic potato plants which have constitutive expression of the P. sajor-caju GPD gene are being bioassayed for osmotic stress resistance.Jeong, Mi-Jeong